Recently, home wastewater treatment systems have become increasingly popular. Prior to the development of home wastewater treatment systems, septic tanks were the conventional manner of cleaning home and small commercial establishment wastes from the water. In view of the great cost associated with connecting a home sewage system with the city sewage system, it is economically beneficial to employ the use of home wastewater treatment systems. Present home wastewater treatment systems are a down-sized, underground version of the treatment processes employed by large central treatment plants.
Essentially, the treatment process correlates with an example found in nature. When a creek runs through rocks and over logs, turbulence is created and oxygen is captured. Aerobic bacteria utilize oxygen in their digestion processes. This allows the creek to purify itself. The home wastewater treatment systems simply employ a speeded-up version of this process in a manner known as "extended aeration". Air or oxygen is brought in by means of an efficient air pump and then diffused into thousands of tiny air bubbles by means of fine air diffusion. As these tiny bubbles move upward through the wastewater, oxygen is captured and the same purification process takes place. Such a system can allow normal household waste water to be reduced to a clear odorless liquid.
One such system has been manufactured and sold by Hydro-Action, Inc. of P.O. Box 12583, Beaumont, Tex. The system is known as the HYDRO-ACTION.TM. system. It is a self-contained automatic system. The HYDRO-ACTION.TM. system incorporates two separate compartments, each performing a specific function in the digestion process. First, raw waste water enters the aeration compartment and is mixed with activated sludge and aerated. An air pump injects large quantities of air into this compartment by means of porous ceramic diffusers located above the bottom perimeter of the aeration compartment. These diffusers create thousands of tiny air bubbles which provide oxygen for the aerobic digestion process and mixes the compartment's entire contents. These tiny bubbles provide better air-to-liquid contact so as to hasten the aerobic digestion process. Aerobic bacteria then use the oxygen in solution to break down the wastewater so as to convert the wastewater into an odorless liquid and gas. Hydraulic displacement causes the mixture to enter the second and final compartment. Due to the calm conditions and sloping walls of the clarification compartment, any remaining settleable material is encouraged to return to the aeration compartment for further treatment. The remaining effluent, upon reaching the outlet piping, is clear and odorless.
During a comprehensive eight month testing program, conducted by Baylor University, in accordance with the National Sanitation Foundation (NSF) Standard 40, the HYDRO-ACTION.TM. system produced an excellent effluent having a quality easily falling under the NSF Class I requirements of less than 30 PPM Bod (5 day) with greater than 85% reduction and less than 30 PPM TSS (Total Suspended Solids) with greater than 85% reduction. The actual HYDRO-ACTION.TM. test averages were 7.23 PPM Bod (5 day) with 96.04% reduction and 5.89 PPM TSS with 96.81% reduction. The HYDRO-ACTION.TM. system produced a clear and odorless effluent. Offensive, embarrasing wastewater odors, which are a common problem with septic tanks, are substantially eliminated by the HYDRO-ACTION.TM. system.
This HYDRO-ACTION.TM. system allows homes to be build on clay soil, rock or high water tables. This system also helps to protect the ground water supplies and eliminates gross pollution of ditches and streams. The effluent discharged from such a system is allowed by some state and local regulatory agencies to be discharged directly to a stream or pond or used to surface irrigate lawns and pastures. In areas where surface discharge is not allowed, subsurface disposal methods can be used with good success.
The use of the Hydro-Action.TM. system becomes more of a problem when high strength wastes are involved. Conventionally, high strength wastes are defined as those wastes which have a biological oxygen demand (BOD) of over 300. High strength wastes often occur from various commercial establishments. Typically, restaurants are a major source of such high strength wastes. The waste flow from a restaurant is five or six times stronger than the waste which passes from a home. When septic tanks were used, the septic tanks are designed relative to the flow rate and not by the biological oxygen demand. If the waste is to be passed subsurface, it is necessary to pretreat and reduce the strength of the waste before it is emitted into a drain field. At the soil interface, it will percolate into the soil. When the BOD is too great, a biological growth will occur on the soil. This biomat will plug the soil interface system.
When extended aeration systems are used for treating such high strength waste, the original systems were designed based upon only the flow rate. When the BOD is great, then the extended aeration system was not designed to dissolve the large quantities of oxygen required to treat such high strength waste. The result was that raw wastewater entered such an extended aeration system and resulted in raw wastewater flowing out of such system. There was simply not enough retention time to effectively treat the waste. A longer retention time is required so as to effectively treat such high BOD wastes.
As a result, a need has developed for the ability to treat such high strength wastes using extended aeration systems. Since such extended aeration systems are often manufactured in standard sizes, it is often difficult to build tanks that are of a sufficient size so as to allow for the suitable retention time of the wastes. Furthermore, it is sometimes difficult to incorporate clarifiers that have a suitable size for accommodating the flow rate from such commercial establishments. Whenever extended aeration systems are built, they must be shipped over public highways to the desired location. As such, the ability to ship becomes a major constraint on the use of such extended aeration systems for treating high strength wastes. The inability to properly dispose of such high strength wastes has become a major problem.
It is an object of the present invention to provide an extended aeration system which is suitable for the treatment of high strength wastes.
It is another object of the present invention to provide a wastewater treatment system which effectively provides suitable retention times for the treatment of high BOD waste.
It is another object of the present invention to provide a wastewater treatment system which is adaptable to the particular flow rates and expected BOD content of the wastes.
It is a further object of the present invention to provide a wastewater treatment system which can provide secondary clarification to the wastewater.
It is a further object of the present invention to provide a wastewater treatment system which is relatively easy to install, easy to use and relatively inexpensive.
It is still a further object of the present invention to provide a wastewater treatment system in which extended aeration tanks are of a suitable size for transport along public highways.
It is still another object of the present invention to provide a wastewater treatment system which avoids the need for septic tanks and municipal sewage line connections.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.